In a conventional brake system, if the brake pedal is depressed very hard, the wheels can lock before the vehicle comes to a stop. In such a case, the stability of the vehicle is reduced if the rear wheels are locked, and maneuverability of the vehicle is reduced if the front wheels are locked, creating an extremely unstable condition.
The Anti-lock Brake System (ABS) modulates the pressure of the brake fluid applied to each front caliper or both rear calipers, thereby preventing the locking of the wheels, whenever the wheels are likely to be locked due to hard braking. It then restores normal hydraulic pressure when there is no longer any possibility of wheel locking.
The ABS on this car is compact, with its hydraulic control system incorporated into one modulator unit. It is a 3-channel anti-lock brake system that has individual control of the front wheels and common control ("select Low") for the rear wheels. "Select Low" means that the rear wheel that would lock first (the one with the lowest resistance to lock-up) determines anti-lock brake system activation for both rear wheels.
PART NAME | MAJOR FUNCTION |
Gear pulser | Attached to the rotating part of the wheel and detects the wheel speed together with the wheel sensor. |
Wheel sensor | Generates pulse signal corresponding to the revolution of the gear pulser. |
ABS control unit | Controls the working of the anti-lock brake system by performing calculations based on the signals from the individual wheel sensors and the individual switches. |
Modulator unit | |
Motor Relay | Controls the ABS pump motor's power supply according to the signal from the ABS control unit. |
Fail-safe relay | Cuts off the solenoid valve ground circuit when the fail-safe device is at work. |